1. Field of the Invention
This invention relates to a new method for synthesizing the zeolite identified as SSZ-16. More particularly, it relates to a method of making SSZ-16 using an organonitrogen template or directing molecule identified herein as DABCO-C.sub.n diquat.
2. Discussion of Relate Art
Zeolitic materials, both natural and synthetic, have been demonstrated to have catalytic properties for various types of hydrocarbon conversion. By using X-ray diffraction, certain zeolitic materials have been shown to have a crystalline structure wherein there are a large number of smaller cavities. These smaller cavities may be interconnected by a number of still smaller channels or pores. Variations in pore dimensions and shapes have been found to effect the adsorptive and catalytic properties of the zeolites. Only molecules of certain dimensions and shapes are able to fit into the pores of a particular zeolite while molecules of a larger dimension or of a different shape are unable to enter the pore in the zeolite crystals. Since the pores in the zeolite accept molecules of certain dimensions while rejecting those of a larger dimension, these zeolites have come to be known as "molecular sieves" and are utilized in a variety of ways to take advantage of these properties. These cavities and pores have been demonstrated to be of a uniform size within a specific zeolite. Because of their unique molecular sieving characteristics, as well as their potentially acidic nature, zeolites are especially useful in hydrocarbon processing as adsorbents and as catalysts for cracking, reforming, and other hydrocarbon conversion reactions.
Such molecular sieves, both natural and synthetic, include a wide variety of positive ioncontaining crystalline aluminosilicates. These aluminosilicates can be described as a rigged three-dimensional framework of SiO.sub.4 and AlO.sub.4 in which the tetrahedra are cross-linked through the sharing of oxygen atoms whereby the ratio of the total aluminum and silicon atoms to oxygen atoms is 1:2. The electrovalence of the tetrahedra containing aluminum is balanced by the inclusion in the crystal of a cation, for example by the inclusion of an alkali metal or an alkaline earth metal cation. This can be expressed by the relationship of aluminum to the cations, wherein the ratio of aluminum to the number of various cations, such as Ca2, Sr/2, Na, K, Cs or Li, is equal to unity. One cation may be exchanged either entirely or partially with another type of cation utilizing ion exchange techniques well know to those skilled in the art. By suitable selection of the cation, it has been possible to vary the properties of a given aluminosilicate.
Prior art techniques have resulted in the formation of a great variety of synthetic zeolites. The zeolites have come to be designated by letter or other convenient symbols, for example: zeolite A (U.S. Pat. No. 2,882,243 issued on Apr. 14, 1959 to Milton), zeolite X (U.S. Pat. No. 2,882,244 issued on Apr. 14, 1959 to Milton), zeolite Y (U.S. Pat. No. 3,130,007 Apr. 21, 1964 to Breck), zeolite ZK-5 (U.S. Pat. No. 3,247,195 issued on Apr. 19, 1966 to Kerr), zeolite ZK-4 (U.S. Pat. No. 3,314,752 issued on Apr. 18, 1967 to Kerr), and SSZ-16 (described in U.S. Pat. No. 4,508,837 issued to Zones on Apr. 2, (1985).
Typically, zeolites are prepared from reaction mixtures having sources of alkali or alkaline earth metal oxides, silica, and alumina. More recently, "nitrogenous zeolite" have been prepared from reaction mixtures containing a "template" consisting of an organic species, usually being a nitrogen compound. By varying the reaction conditions under which the zeolite is formed and the composition of the reaction mixture, different zeolites can be formed even if the same template is used. For example, zeolites ZK-4, ZSM-4, faujasite and PHI, have all been prepared from solutions containing tetramethylammonium cations.
Although most experiments reported as producing nitrogenous zeolites have used fairly simple organic template species, such as tetraalkylammonium cations or alkylenediamines, several experiments have reported using more complex organic species. U.S. Pat. No. 3,692,470, discloses preparing ZSM-10 from 1,4-dimethyl-1,4-diazoniabicyclo[2,2.2.-]octane. U.S. Pat. No. 3,832,449, Rosinski et al., Aug. 27, 1974, discloses preparing ZSM-12 from the reaction products of alkylene dihalides with complex amines or nitrogen heterocycles, U.S. Pat. No. 4,285,922, Audeh, Aug. 25, 1981, discloses preparing ZSM-5 using 1-alkyl, 4 aza, 1-azonia-bicyclo[2.2.2]-octane, 4-oxide halides.
U.S. Pat. No. 4,508,837, the entire disclosure of which is incorporated herein by reference, describes a process for making a crystalline aluminosilicate identified as SSZ-16 using as a template derivatives of the organic species of 1, 4-di(lazoniabicyclo [2.2.2] octane) lower alkanes. One impediment in preparing the SSZ-16 crystalline structure for commercial use is the high cost of this organonitrogen template. It is therefore an object of this invention to provide a method for producing the zeolite SSZ-16 using a less costly template.